90 Meteorological Ohervations. [August, 



as shown by the diminished size of the streams in summer, a fact 

 that has been regarded with anxiety by mill owners, and which 

 indicates the approach of a time when much trouble maybe occa- 

 sioned from this source. This is to be ascribed to the gradual 

 destruction of the forests, and conversion of the swamps into 

 meadows; by which means, not only less evaporation takes place 

 from the general surface and consequently less rain produced, but 

 the rills are exposed to the sun and dried up. 



In the spring season, and in the early part of summer, it is 

 common to observe those radiating beams of yellow and blue af- 

 ter sunset, which have been so often observed and admired in 

 western New York. These belts of sunlight and clear sky, doubt- 

 less caused by the interception of a portion of the sun's rays by 

 distant clouds, were on one occasion noticed extending across the 

 entire heavens, and disappearing in the east. These parallel 

 belts of light, by the known laws of perspective, seemed to di- 

 minish in breadth and converge in the opposite points as if an- 

 other luminary was about to rise in the east. 



There almost invariably occurs, during the year, two well 

 marked seasons of smoky weather, in June and in November. The 

 latter period is the well known American peculiarity, the Indian 

 summer, which seldom fails to beautify with its bland air and 

 dusky tints, the gloom of autumn, and usher in the winter. Is it 

 not probable that this period corresponds to the halcyon days of 

 the ancients? although that event occurred later than our Indian 

 summer, it being the seven days that precede and follow the 

 winter solstice. 



Not having met with a satisfactory theory to explain this phe- 

 nomenon, I have been induced to frame a theory of my own by 

 which to account for it. Two facts are to be noticed; the lull 

 of the atmosphere, and the smoky hue of the air. From the oc- 

 currence of this calm period on both continents, and at the transi- 

 tion between winter and summer, we may infer that it is dependent 

 upon a cause as general as that which causes the change of sea- 

 sons. The prevailing direction of winds in summer being from 

 some point south of west, while in winter the winds are from a 

 northwardly direction, is a fact so general as to accord with the 

 experience of all, aside from meteorological observations. The 

 change in the prevailing course of the winds, must be attended' 

 by a period of rest in the same manner as it would l)e, if the 

 gentle current of a river was reversed, by a slight change of level 

 in its two extremities. 



The cause of the prevalence of soulheily winds in summer, and 

 the opposite in winter, is doubtless related to the revolution of the 

 earth round the sun, in the same manner as the seasons, and due 

 to the general flow of air from the cold hemisphere of the globf- 



